In the wake of two major Navy ship collisions in the Pacific this summer that caused the deaths of 17 sailors, government oversight officials found nearly 40 percent of warfare certifications for Japan-based surface combatants were expired, and scaled-back crews have increased the workload for sailors in the Pacific.

John Pendleton, the Government Accountability Office director for defense force structure and readiness issues, was set to discuss the office's findings Thursday at a House Armed Services Committee hearing on the causes of the two recent collisions.

Military.com reviewed a copy of his testimony ahead of the hearing. CNN first reported its contents.

The findings, the report suggests, call into question not only the Navy's strategy for operating forward-deployed ships, but its ability to adequately maintain and operate the larger fleet it wants.

The service has called for growth to a 355-ship Navy, up from its current fleet of 277.

"Looking to the future, the Navy has plans to grow its fleet by as much as 30 percent, but it has not yet shown the ability to adequately man, maintain, and operate the current fleet," Pendleton wrote in his prepared testimony.

"These readiness problems need to be addressed and will require the Navy to implement our recommendations -- particularly in the areas of assessing the risks associated with overseas basing, reassessing sailor workload and the factors used to size ship crews, and applying sound planning and sustained management attention to its readiness rebuilding efforts," he wrote.

The GAO found that a lack of scheduled training periods for Pacific-based ship crews contributed to the crews increasingly continuing to operate with expired warfare certifications, including certifications for seamanship.

As of June of this year, the office found, 37 percent of warfare certifications for all cruisers and destroyers homeported in Japan were expired, a fivefold increase since May 2015.

In the last decade, the Navy has doubled the percentage of its ships homeported overseas, with an emphasis on expanding its presence in the Pacific as part of the service's pivot to that part of the world.

However, the GAO found in 2015 that Japan-based cruisers and destroyers lacked dedicated time for training and sustainment in keeping with the Navy's own optimized fleet response plan, and instead practiced training "on the margins" -- whenever time and conditions allow.

Damage to the portside is visible as the guided-missile destroyer USS John S. McCain (DDG 56) steers towards Changi Naval Base, Republic of Singapore, following a collision with the merchant vessel Alnic MC while underway east of the Straits of Malacca and Singapore.U.S. Navy photo

The more recent report found moreover that the Navy was taking risks by scaling back crew size and piling work onto remaining sailors, who sometimes work more than 100 hours a week while deployed.

The Navy in 2001 began reducing crew size in its "optimal manning" initiative, designed to complement manpower with new technology.

In 2010, the service concluded the initiative was adversely affecting readiness, and phased it out in the years that followed.

But the GAO found crew sizes and personnel costs remained somewhat scaled back, and that crews were further reduced during in-port periods, which increased sailors' workload then.

Investigations continue into the cause of the collisions of the destroyers John S. McCain and Fitzgerald with commercial vessels in two separate incidents in the Pacific this summer.

The McCain collided with a Liberian-flagged tanker east of the Straits of Malacca near Singapore Aug. 21, resulting in the deaths of 10 sailors aboard.

Guided-missile destroyer USS John S. McCain (DDG 56) moored pier side at Changi Naval Base, Republic of Singapore following a collision with the merchant vessel Alnic MC while underway east of the Straits of Malacca and Singapore on Aug. 21.DoD photo

The two deadly collisions within months of each other represent disasters unprecedented in recent years.

Since 2009, there have been only 16 collisions or groundings of any kind involving Navy vessels, and only one other resulted in a fatality: a 2012 incident in which a special operations craft collided with a civilian fishing boat near the Philippines, killing a fisherman.

After more than a decade of research and development and upwards of $500 million in funding, the Navy finally plans on testing its much-hyped electromagnetic railgun on a surface warship in a major milestone for the beleaguered weapons system, Navy documents reveal.

Just in time for many high school graduations, Gov. Ron DeSantis has signed into law a measure ensuring that seniors in the military may wear their dress uniforms instead of a cap and gown at their ceremonies.

DeSantis, a former Navy officer, approved SB 292 to become law upon his signature, which came Thursday.

STATEN ISLAND, N.Y. -- Congress fell short ahead of Memorial Day weekend, failing to pass legislation that would provide tax relief for the families of military personnel killed during their service.

Senators unanimously approved a version of the bipartisan Gold Star Family Tax Relief Act Tuesday sending it back to the House of Representatives, where it was tied to a retirement savings bill as an amendment, and passed Thursday.

When it got back to the Senate, the larger piece of legislation failed to pass and make its way to the President Trump's desk.

Two airmen were administratively punished for drinking at the missile launch control center for 150 nuclear LGM-30G Minuteman III intercontinental ballistic missiles at F.E. Warren Air Force Base in Wyoming, the Air Force confirmed to Task & Purpose on Friday.

Two F-35A Lightning II Joint Strike Fighters recently flew a mission in the Middle East in "beast mode," meaning they were loaded up with as much firepower as they could carry.

The F-35s with the 4th Expeditionary Fighter Squadron took off from Al Dhafra Air Base, United Arab Emirates to execute a mission in support of U.S. forces in Afghanistan, Air Forces Central Command revealed. The fifth-generation fighters sacrificed their high-end stealth to fly with a full loadout of weaponry on their wings.